CVE-2025-54423: Copyparty Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-9q4r-x2hj-jmvr
Share
CVSS 5.4
CWE-79
Published
Advisory Summary

CVE-2025-54423 is a MODERATE (CVSS 5.4) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Copyparty libraries in the PyPI ecosystem. The issue involves copyparty has dom-based xss vulnerability when displaying multimedia metadata. Remediation is available by upgrading affected packages to version 1.18.5.

CVE-2025-54423 at a Glance

CVE Identifier CVE-2025-54423
GHSA Identifier GHSA-9q4r-x2hj-jmvr
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Copyparty
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2025-54423

To remediate this vulnerability, upgrade all affected Copyparty dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

copyparty fixed: 1.18.5 
pip install copyparty>=1.18.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show copyparty

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2025-54423, inspect your installed packages using pip:

pip show copyparty

Analyze the terminal output to locate any version of Copyparty in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.18.5), your application is affected.

Note: The pip show copyparty command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Copyparty, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary An unauthenticated attacker is able to execute arbitrary JavaScript code in a victim's browser due to improper sanitization of multimedia tags in music files, including `m3u` files. ### Details Multimedia metadata is rendered in the web-app without sanitization. This can be exploited in two ways: * a user which has the necessary permission for uploading files can upload a song with an artist-name such as `<img src=x onerror=alert(document.domain)>` * an unauthenticated user can trick another user into clicking a malicious URL, performing this same exploit using an externally-hosted m3u file The CVE score and PoC is based on the m3u approach, which results in a higher severity. ### PoC 1. Create a file named `song.m3u` with the following content. Host this file on an attacker-controlled web server. ```m3u #EXTM3U #EXTINF:1,"><img src=x onerror=alert(document.domain)> - "><img src=x onerror=alert(document.domain)> http://example.com/audio.mp3 ``` 2. Craft and share the malicious URL: ``` http://127.0.0.1:3923/#m3u=https://example.com/song.m3u ``` ### Impact Any user that accesses this malicious URL is impacted.

CVE-2025-54423 Affected Copyparty Versions

1 component(s)
Fixed Versions:
1.18.5
Product / Package Ecosystem Affected Versions Fixed Version
copyparty
pypi/copyparty
PyPI
< 1.18.5
1.18.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/9001/copyparty/security/advisories/GHSA-9q4r-x2hj-jmvr
NVD — CVE-2025-54423 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-54423
Security Fix Commit FIX COMMIT
https://github.com/9001/copyparty/commit/895880aeb0be0813ddf732487596633f8f9fc3a6
Copyparty Source Repository REPOSITORY
https://github.com/9001/copyparty
Copyparty Release RELEASE
https://github.com/9001/copyparty/releases/tag/v1.18.5

Frequently Asked Questions

What is CVE-2025-54423?
CVE-2025-54423 is a security vulnerability in Copyparty involving copyparty has DOM-Based XSS vulnerability when displaying multimedia metadata under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Copyparty versions are affected?
Affected versions include releases prior to 1.18.5 across affected packages: copyparty.
What version fixes CVE-2025-54423?
Upgrading to 1.18.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is copyparty affected?
Yes, copyparty is affected in releases prior to 1.18.5. Upgrade your dependency to 1.18.5 or later.
What is the CVSS score of CVE-2025-54423?
CVE-2025-54423 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2025-54423?
CVE-2025-54423 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check PyPI dependencies for CVE-2025-54423?
Run the dependency tree command: 'pip show copyparty'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9q4r-x2hj-jmvr",
  "modified" : "2025-07-29T12:34:32Z",
  "published" : "2025-07-28T16:41:44Z",
  "aliases" : [ "CVE-2025-54423" ],
  "summary" : "copyparty has DOM-Based XSS vulnerability when displaying multimedia metadata",
  "details" : "### Summary\n\nAn unauthenticated attacker is able to execute arbitrary JavaScript code in a victim's browser due to improper sanitization of multimedia tags in music files, including `m3u` files.\n\n### Details\n\nMultimedia metadata is rendered in the web-app without sanitization. This can be exploited in two ways:\n\n* a user which has the necessary permission for uploading files can upload a song with an artist-name such as `<img src=x onerror=alert(document.domain)>`\n* an unauthenticated user can trick another user into clicking a malicious URL, performing this same exploit using an externally-hosted m3u file\n\nThe CVE score and PoC is based on the m3u approach, which results in a higher severity.\n\n### PoC\n1.  Create a file named `song.m3u` with the following content. Host this file on an attacker-controlled web server.\n\n    ```m3u\n    #EXTM3U\n    #EXTINF:1,\"><img src=x onerror=alert(document.domain)> - \"><img src=x onerror=alert(document.domain)>\n    http://example.com/audio.mp3\n    ```\n\n2.  Craft and share the malicious URL:  \n\n    ```\n    http://127.0.0.1:3923/#m3u=https://example.com/song.m3u\n    ```\n\n\n### Impact\nAny user that accesses this malicious URL is impacted.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "copyparty"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.18.5"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.18.4"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/9001/copyparty/security/advisories/GHSA-9q4r-x2hj-jmvr"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-54423"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/9001/copyparty/commit/895880aeb0be0813ddf732487596633f8f9fc3a6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/9001/copyparty"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/9001/copyparty/releases/tag/v1.18.5"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-07-28T16:41:44Z",
    "nvd_published_at" : "2025-07-28T20:17:48Z"
  }
}